Treatment of pyrites liquor for winning metals therefrom.



JOH N HERBERT 'PHWAITES, OF PETERBOROUGH, ENGLAND.

TREATMENT Oil FI'BITES LIQUOR FOR WINNING METALS THEREIROM.

Specification 01' Letters Patent.

' Pltentod. May 11,1900.

Application filed July 8., 1908. Serial No. 442,620..

To all whom it may concern:

'Peterborough, in the county of Northampton, England, chemical engmeer, have i t vented certain new and useful Improvemerits in the Treatment of Pyrites L1 uors for Winning Metals Therefrom, of whic the following is a specification.

This invention relates to the treatment of liquors obtained from pyrites, pyrites cinder and the like. for the metals therefrom and for preparing the liq uors so that. white zinc.- compounds can be precipitated therefrom.

The invention deals only with li uors practically free fromcopper, which wil be assumed to have been removed as far as practicable if present.

For the u-rpose of this. invention there is added tot e hquor, whether sulfate of soda has been removed or not, zinc oxid whether h drated or carbonated or not, in the form 0? a cream or fine powder or other effective state, the reactions being represented by the following chemical equations The quantity of zinc oxid necessary is slightly more than that chemically equivalent to the iron present in the solution, a convenient outside excess being five per cent. The whole is well mixed by constant or intermittent agitation and the iron compounds present are oxidized by blowing in or otherwise supplying air, oxygen or other oxidizing agent incapable of peroxidizing and pre cipitating cobalt in this solution. To hasten the action the liquor is heated and is referably maintained at or near boiling point 90 C. being a convenient temperature. The zinc oxid dissolves in the liquor and the iron is recipitated -as a hydrated oxid in a rca-"ly separable form sometimes contain ing basic iron compounds; alumina, if pres,- ent, is also precipitated provided the temperature is at or almost at the boiling point.

In order to economize the oxidizing agent and time, the precipitation of the iron may be carried out in two or more stages, the precipitate being removed by filtration or otherwise between the stages and care being purpose of recovering.

'taken that the amount of zinc precipitant added at each stage is not so large that some of it remains undissolved and is removed with the iron precipitate; should this happen, the 1precipitate may be added to another bate of the liquor to recover the zinc in working u that batch.

Greater atitude in the addition of the zinc precipitate is allowable if chlorids are present, as a small excess of the former dissolves as a zinc oxychlorid and loss isthus min-imized; it is therefore convenient, though by no means necessary, to have chloride present for this reason and also because the reactions are completed in less time,'and, if any known apparatus be used which is adapted to break up or prevent the formation of clots or cores-of the precipitant, the excess, if any, of the latter necessary for complete removal of the iron, is very slight. The time required for the oxidation of the iron depends upon the quantity of ferrous iron present, on the temperature and largely on the form of apparatus used, an adequate. air su ly being of course provided. I

he iron precipitate formed is denser than iron hydrates precipitated in-the usual ways it subsides quickly and is easily filtered and washed, even though it contains alumina. When washed it is suitable for many purposes, for example the preparation of oxid paints.

Alkalies or alkaline earths, either caustic or carbonate may be used instead of the zinc compounds for precipitating the iron, but the precipitate produced is bulky and difficult to'manipulate, especially if alumina is present, and on the large scale their use is not advisable. Should it be inadvisable to obtain oxids of manganese and cobalt as separate roducts, thev iron oxid precipitate need not e separated from the liquor until after the stage next to be described.

The liquor is now treated with an alkaline hypochlorite, or with an alkali or zinc oxid and chlorin, or with an equivalent peroxidi-zing material or mixture, and it is heated to expedite the reaction. Manganese, cobalt, and nickel, or such of them as may be present, are thus precipitated, the following equations being typical of the reaction The precipitate is filtered or otherwise re moved and is worked up in any known manner to obtain the metals or their compounds. If, after the reviousoperation any; iron was left in the so ution it Wlll be contained in the precipitate of oxids'produced atthis stage; there must, however, be .no trace of this metal left in. the liquor now if the purest white sulfid pi ments of zinc are to be easily obtaine Occasionally a small amount of permanganate may be formed durin the peroxidizlng treatment, in which case tlle liquor will be colored pink; this ma be disre arded if treatment with an alkai sulfid f0 lows before the final liquor containing zinc salts is treated in any way for producing zinc compounds; but if such sulfid treatment is not to follow the permanganate is best reduced by a suitable agent and the manganese precipitated by a careful repetition of the peroxidizing treatment.

To the liquor is next added a quantity of a soluble sulfid or of sulfureted hydrogen sufficient to precipitate any cadmium which may be present, according to the equations 00101 Na,S OdS 2Na0l,

together with certain of the metals which may have remained in solution notwithstanding the previous treatment. The precipitate formed is filtered or otherwise removed, andmay be worked up, if desired, for the metals contained in it, or their compounds. The aforesaid sulfid treatment may be applied either before or after the removal of the iron from the liquor, instead of at this stage; as, however, it constitutes a remedy against possible careless working or accident, it is preferable to apply it after the peroxidizing treatment. It is obvious that if a sample of the liquor after the last named treatment gives a recipitate con sisting only of white zinc su fid on the addition of an alkali sulfid, the treatment to rem'ove cadmium or other metals may be omitted.

There now remains a liquor containing chlorids or sulfates or other salts of zinc, with or without other salts such as those of sodium, which liquor ields by known treatment zinc compounds or white zinc pigments, such as carbonate, oxid or sulfid according to the following typical equations:

ZnCl Na CO ZnCO 2NaCl ZnSO BaS ZnS BaSo and the li uor remaining from such treatment ma e made to yield any other compounds t at it may contain, such as sodium sulfate or chlorid or both.

In my British specification No: 27515 of 1906 I have described a-mode of treating or utilizing pyrites cinder and other metallic sulfids ow in sulfur,.'and'I1do."not herein claim anything described or claimed in that specification.

Having thus' described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim 1. A treatment of liquors obtained from pyrites cinder or the like and from which co per has been removed if resent, consisting in adding to the liquor a zinc compound adapted to precipitate iron as hydrated ferric oxid, then peroxidizing the mixture, then removing the precipitate thus formed and finally adding a sulfid adapted to remove materials which would prevent the precipitation of white zinc sulfid from the li uor.

2. A treatment of liquors obtaine from pyrites cinder or the like and from which copper has been removed if present, consisting in adding to the liquor a zinc compound adapted to precipitate iron as hydrated ferric oxid, then oxidizing ferrous iron in the liquor, then removing the precipitate thus formed, then peroxidizinlg the liquor, then removing the preci itate t us formed and finally adding a en (1 adapted to remove materials which would revent the precipitation of White zinc su 'd from the liquor.

3. A treatment of liquors obtained from pyrites cinder or the like and from which co er has been removed if present, consistin in t adding to the liqf or a sulfid adapte to precipitate metals 0 the copper and lead groups, then separating the precipitate thus produced, then adding to the liquor a compound of zinc adapted to preci itate hyrated ferric oxid, then peroxi ing the mixture and finally removing the precipitate thus produced.

4. A treatment of liquors obtained from pyrites cinder or the like and from which copippr has been removed if present, consistin 1n st adding to the liquor a sulfid adapte to precipitate metals of the copper and lead groups, then separating the precipitate thus produced, then adding to the liquor a compound of zinc adapted to precipitate hydrated ferric oxid, then oxidizlng ferrous iron in the li uor, then removin the precipitate I precipitate metals of the copper and lead lead groups, then removing the reci itate,

groups, then removing the precipitate thus then peroxidizing the li uor an fina y reormed, then peroxidizing the liquor and moving the precipitate t us formed.

finally removing the precipitate thus formed. In testimony whereof I have signed-my 15 6. A treatment of liquors obtained from name to this specification in the presence of pyrites. cinder or the like and from which coptwo subscribing witnesses.

per has been removed if present, consisting in adding to the liquor a zinc compound adapt- JOHN HERBERT THWAITES' ed to precipitate iron as hydrated ferric Witnesses: 0 oxid, then adding to the liquor a sulfid adapt- Gno. J. W. FRANKLIN,

ed to precipitate metals of the copper and WALTER J. SKERTEN. 

